How to Prep Vehicles for Winter Weather

Here is a roundup of guidelines for winterizing vehicles from some of these manufacturers.


George Daniels, vice president of service operations for Hino Trucks, says when going into the winter season, the company advises its customers to pay attention to:

Tires: To maximize traction, make sure tire air pressures are correct and tread condition is good.

Brakes and ABS: Inspect brake lining condition and check for leaking wheel seals. Ensure proper braking from each wheel and operation of ABS to keep control and minimize skidding.

Wipers, washers, heaters and defrosters: These need to be in good working order to allow clear vision at all times.

Fuel system: To minimize chances of fuel gelling, maintain fuel filters, drain fuel water separators and fuel tanks of any accumulated water. Verify operation of the fuel heater, if equipped.

Air system: Drain all air tanks daily. Service the air drier.

Batteries and charging systems: Check and clean all battery connections. Load test to verify battery condition. Check starter condition and operation. Check charging system for proper operation.

Cooling system: Verify protection level and quality of the coolant. Check all fan belts and coolant hoses.

Block heater: Check for proper operation.


Brian Tabel, Isuzu Commercial Truck of America’s retail marketing manager, says it is important to focus on the engine, operating systems and tires when the weather starts cooling down.


Vitals areas that should be checked:

  • Fuel filter and water separator. If neglected, they can contribute to hard starting. Case in point, if water is permitted to accumulate in the primary filter it will freeze and make starting the engine impossible.
  • Fuel tank vent. Make sure it is open.
  • Refuel at the end of a day’s operation. Moisture will condense in an empty fuel tank. Therefore, fuel tanks should be filled before leaving the vehicle standing for an extended period of time.
  • Check the type of oil being used. Using the proper viscosity oil will make starting easier down to -10 degrees F. Consult the vehicle’s owner’s manual for the recommended oil viscosity.
  • For weather below -10 degrees F, consider adding an engine block or oil pan heater to make starting easier.
  • Winterize the cooling system. Use a 50/50 mixture (48/52 for colder climates) of the vehicle manufacturer’s recommended coolant and water for freeze protection. Maintaining the cooling system also prevents overheating during warmer climate operation.
  • Do not use “starting aids” in the air intake system. Such products can cause immediate engine damage.
  • Check that all fluids are at their proper level.


Be aware that diesel fuel is sensitive to temperature, warns Tabel. “Consider the chemistry. All diesel fuel contains paraffin components which are high in energy value and help improve fuel economy.

“But, when temperatures dip below 20 degrees F, the paraffin components begin turning into wax flakes, and if temperatures are low enough, these flakes can obstruct the fuel filters and stop fuel from reaching the engine leaving the vehicle stranded and cold.”

At low temperatures, wax flakes are more likely to form in Number 2-D fuel than in Number 1-D, or “winterized” Number 2-D fuel, he says. “For best operation at temperatures below 20 degrees F, use Number 1-D or Number 2-D that has been blended with Number 1-D for winter use.

“When temperatures are consistently below or near 0 degrees F, use Number 1-D if at all possible. Bear in mind, however, that even Number 1-D fuel will form wax flakes when temperatures are extremely low.”


  • Make sure the air filter is clean for consistent engine operation.
  • Check and, if necessary, clean the battery posts and make sure the connections are tight. Check the condition of the battery, as freezing conditions drain a battery faster. Replace the battery if it is close to the end of its lifecycle.
  • Install new windshield wiper blades.
  • Check the windshield washer fluid reservoir and be sure it is filled with the proper fluid to avoid freezing.
  • Inspect for worn-out parts, belts and hoses. Cold weather can cause belts to crack and break. Bulging hoses indicate weak spots in the hose and should be replaced as needed. Replace any parts that are worn down or damaged.
  • Check the heater to make sure it is operating properly.
  • Check all fluids to ensure there is enough oil, coolant and other necessary fluids.


Check tire tread, Tabel advises. Worn tires can compromise a vehicle’s traction when it is wet and slippery. To get the best traction, tires must be properly inflated.

“If you use chains, be sure they are the correct size for your tires and know how to properly install them.”


One of the newest items in the maintenance checklist appears courtesy of the EPA 2010 emissions regulations, specifically for diesel engine models using urea-based diesel exhaust fluid (DEF) in their emissions control systems,” observes Bill Mohr, Mitsubishi Fuso Truck of America’s director of service operations. “The freezing point of DEF is 12 degrees F, so it is likely to freeze in many northern locales.

“However, virtually all medium duty trucks’ emissions systems are designed to accommodate this. The 2012 FUSO Canter, for instance, includes both a DEF tank heater and line heater to ensure proper operation even in extreme cold.”

He provides these other winter maintenance recommendations:

  • Check and maintain engine heaters. While medium duty trucks have typically used block heaters to keep engine oil warm, some newer models use oil-pan heaters. These units are mounted to the pan and heat the engine pan and oil directly, so they can be smaller and more efficient than block heaters. Block heaters, on the other hand, are typically mounted 12 inches or so above the oil pan and generally heat the engine coolant, which in turn conducts heat to the block to aid in cold-weather starting.
  • Check coolant both for proper level and for longevity. “Coolant life is typically specified by the coolant manufacturers at 24 months, so if coolant is older than that, the system should be flushed and the coolant replaced,” he says. “While the antifreeze properties of the coolant may not dissipate with time, additives that provide corrosion protection, anti-gumming and other ancillary protection functions do break down with time, compromising overall performance.”
  • Service the fuel filter and drain the water separator to prevent freezing.
  • Test the battery and clean the connections. While battery degradation occurs much more rapidly in hot weather, it is under the high starting load batteries face in cold weather that they typically fail.
  • Check windshields for minor chips and pitting. As temperatures decrease and sheet metal contracts, stress on windshields can increase. Have small chips repaired to help avoid crack propagation and the need for a full windshield replacement.
  • Check windshield wiper blade condition and replace as necessary.
  • Check and fill windshield washer reservoirs regularly, being sure to use proper winter dilution levels.
  • Check heater/defroster operation, including function/position of the directional vanes in the system to assure effective defrosting.
  • Check tire condition and make sure tread thickness is a minimum of 5/32-inch for winter driving. For harsh winter conditions, consider a truck with a limited slip differential - an option on many commercial trucks.
  • Check exhaust systems, particularly on gasoline engine models, to assure they are free of leaks. Sitting in slow-moving traffic, creeping because of heavy weather or parked with the engine running to maintain cab temperature can increase the risk of carbon monoxide entry into the cabin.
  • On diesel-engine models, check glow plug operation.
  • Check ABS operation at the start of the winter season, even if this requires a variance from the regular brake maintenance schedule.
  • Clean the cab, body and undercarriage regularly to remove road salts in heavy snow areas.
  • Keep the radiator frontal surface clean and free of bugs, dirt and debris.
  • Check the operation of heated mirrors if so equipped.
  • Check all belts and hoses, and replace as necessary.

Remember that safety extends beyond your own fleet to people you share the road with, so check mud flaps regularly, and replace as necessary.


According to Randall Ray, manager, engine sales and marketing, Navistar, one of the simplest ways to keep diesel trucks running during winter is to follow the recommended warm-up times provided in the engine manual. “This allows lubricating oil to establish a film between moving parts,” he explains.

After the five-minute warming period, begin operating at reduced engine speeds and load until the vehicle reaches operating temperature.

His other suggestions:

Check the truck’s batteries and make sure they are fully charged. Freezing conditions drain a battery faster. Replace the battery if it’s close to the end of its lifecycle. Make certain batteries are securely mounted and connections are tight and clean.

Proper oil grade is essential. The Society of Automotive Engineers (SAE) defines oil viscosity (thickness) by grade. Colder temperatures require lower grade oils for correct flow during starting. Higher temperatures, in turn, call for higher grades for proper lubrication.

Check the fuel. As the seasons change, it is a good idea to check the fuel grade, as well as the cetane rating on the pump. The higher the cetane number, the easier the vehicle will start in cold weather.

When pulling back into the lot at the end of the day, or stopping for the night, fill the fuel tank, drain the water from the fuel filter housing, check the oil level and clean external surfaces of the engine and accessories to prevent dirt or snow build-up.

“Water and contaminants that occur in the fuel have a direct impact on the service life and performance of diesel engines, he notes. “They can reduce engine performance and ruin components, such as fuel pumps and injectors.

“During the winter, condensation forms on the inside of a warm fuel tank as it cools. Filling the fuel tank at the end of the day reduces how much condensation will collect. This might seem to be a minor point, but it can help reduce the chances of costly downtime and expensive repairs.”


UD Trucks North America’s Larry Schultz, vice president of aftermarket, offers these recommended maintenance steps to help keep a fleet operating trouble-free during the harsh winter months:

  • Check and adjust antifreeze protection to at least -22 degrees F.
  • Replace the engine oil, oil filter, transmission fluid and differential lube oil.
  • Inspect the engine drive belts, engine and heater hoses and radiator mountings.
  • Check the charging system, inspect and load test batteries and clean and tighten battery cables. A partially charged battery is subject to damage by freezing temperatures.
  • Replace the fuel filters, inspect all flexible fuel hoses and drain any sediment or moisture from the fuel tanks.
  • Check the preheater or glow plug operation.
  • Check the operation of the coolant heater if equipped.
  • Check the air dryer and replace the air dryer desiccant/filter every 12 months, regardless of mileage. Drain all moisture from the air tanks.
  • Replace windshield wiper blades. Check the operation of the windshield washer system, defrosters and heater.
  • Inspect the air cleaner restriction gauge and replace the air filter if required.


For trucks and trailers, winter accelerates all the bad things that can happen on the road to electrical systems, says Mark Blackford, national fleet manager at Grote Industries.

Water is bad, but salt water and ice build-up is worse, he notes. “The basic problem is that salt water corrodes wiring at a more rapid rate than plain summer water and also wicks farther along wiring than rain water.”

Before the ice and salt brine season starts, Blackford recommends taking these measures:

1. Check all electrical connections as loose connections are prime water entry points. Make sure all interior surfaces are liberally coated with anti-corrosion grease and check that the connection closes correctly and forms a tight closure.

2. Frayed wiring is a perfect entry point for salt water. It will enter any opening in the insulation and wick salt water through the harness. Therefore, inspect all wiring and make sure all frayed wiring is spliced out and properly sealed.

3. Any wires that hang down from their correct runs are prime candidates for ice build-up. As ice accumulates, the increased weight pulls on the wiring, causing more fraying, loose or severed connections, lamp dislocations and stress on splices. If a wire or cable pulls out completely, you can lose your lighting.

Wiring needs to be tucked and tied up into its run so that ice can’t dislodge it. If a wire has to be exposed, a wire tie can often prevent failure due to ice build-up.

4. Choosing a harness design that uses male pin lamp terminations “is always a safer and better idea in all seasons, but especially so in winter,” Blackford says. “If ice does succeed in pulling wiring free of a lamp, the free wire will not short out its circuit by contacting metal surfaces on the trailer.”

5. Check to see that drip loops are not in a place where unseen ice builds up. In winter, drip loops no longer always deflect water as they do when the temperature is above freezing.

6. There should be no taped splices in the wiring. All splices should be heat-sealed with shrink splices. This is always true, but winter grime build-up often hides splices that need attention.

7. Battery connections need to be checked to make sure the required current is present. Terminals should be cleaned, tightened and greased to protect the battery and the overall electrical service.

All truck OEMs agree that the initial time and associated cost of winter preventative maintenance is well worth the investment as it will keep vehicles operating reliably when the snow falls and the temperatures drop.